Air driven turbine



Aug. 22, 1961 A. B. BLACKBURN AIR DRIVEN TURBINE 2 Sheets-Sheet 1 FiledOct. 22. 1959 SQ INVEEUR. 0/022 5. fl/ackwvz BY H15 ATTOK/Vfy 1961 A. B.BLACKBURN 2,997,109

AIR DRIVEN TURBINE Filed Oct. 22. 1959 2 Sheets-Sheet 2 RPS 54 A051911/61 E IN 0568555 IN V EN TOR. 0/027 5. Blew/M11171 B Y United ratesPatented Aug. 22, 1961 2,997,109 AIR DRIVEN TURBINE Alan B. Blackburn,Troy, Ohio, assignor to General Motors Corporation, Detroit, Mich., acorporation of Delaware Filed st. 22, 1959, Ser. No. 848,083 8 Claims.(Cl. 17068) This invention pertains to air driven turbines, andparticularly to variable pitch air driven turbines including governormeans for maintaining turbine speed within preselected limits.

Heretofore, ram air driven turbines have been manufactured havingcentrifugally responsive flyweights in the form of counterweightssupported for rotation about axes coincident with the longitudinal axesof the adjustable pitch turbine blades. A ram air driven turbine havinggoverning means of this type is disclosed in Hoot et al. Patent#2851006, and a slightly different form of the governor is shown inBlackburn et a1. Patent #2876,- 84-7. The present invention relates toan improved springflyweight governor of the blade counterweight typeincluding a modified governor linkage that permits a larger blade angleexcursion while maintaining a substantial linear relationship betweenthe blade angle and the turbine speed. Accordingly, among my objects arethe provision of governor means of the spr-ing-flyweight type for avariable pitch driven turbine including means for increasing the rangeof pitch positions within the governing regime; the further provisionofa spring-flyweight droop governor having connecting links with camsurfaces thereon; and the still further provision of a springfiyweightdroop governor having a pair of sliders, one of which coacts with thecam surfaces on the governor connecting links to extend the governingrange.

The aforementioned and other objects are accomplished in the presentinvention by mounting the governor spring with its axis coincident withthe horizontal axis of the turbine and embodying a pair of sliders whichare operable to compress the governor spring. Specifically, the ram airturbine comprises a hub suitably connected to a shaft for impartingrotation thereto. A pair of diametrisally adjustable pitch blades anddiametrically opposed fixed pitch blades are mounted in the hub, thisarrangement being similar to that disclosed in copending applicationSerial No. 762,992, filed September 24, 1958, in the name of Robert L.Sayre and assigned to the assignee of this invention.

The adjustable pitch blades are bearing supported for rotation abouttheir longitudinal axes between predetermined pitch positions. Each ofthe adjustable pitch blades has spline connected thereto a governorcounterweight, and both governor counterweights are connected by linksto a first slider. The governor spring, located coaxially of thehorizontal axis of the turbine has its outer end in engagement with afixed retainer and its inner end engaging a second slider. Duringmovement of the blades from their minimum, or low positive pitchpositions, towards the high positive pitch position, the first slidermoves outwardly towards the front of the hub thereby compressing thegovernor spring. The links are formed 'with cam surfaces arranged toengage the second slider at a predetermined high pitch position so as tofurther compress the governor spring. This arrangement extends the ationand performance of the governor.

Further objects and advantages of the present invention will be apparentfrom the following description, re-

ference being had to the accompanying drawings, wherein a preferredembodiment of the present invention is clearly shown.

In the drawings:

FIGURE 1 is a front view, in elevation, of a ram air turbine constructedaccording to the present invention.

FIGURE 2 is an enlarged, fragmentary view, partly in section and partlyin elevation, taken along line 22 of FIGURE 1.

FIGURE 3 is a view similar to FIGURE 2 with the adjustable pitch bladesat a high blade angle.

FIGURE 4 is a graph showing the improved operation of the governor.

FIGURE 5 is a fragmentary view, partly in section and partly inelevation, taken along lines 55 of FIGURE 2.

With particular reference to the drawings, the air driven turbineincludes a frusto conical spinner 10 which encloses the root portions ofadjustable pitch blades 12 and fixed pitch blades 14. The fixed pitchblades 14, as seen in FIGURE 2, have root portions 16 secured to a hub18 by means of transversely extending pins 20. In the disclosedembodiment, the fixed pitch angle of the blades 14 may be on the orderof a positive 20 as measured from the plane of rotation. Thus, when theturbine is positioned in a moving air stream the fixed pitch blades 14,which are diametrically opposed, will always develop a positive windmilltorque tending to rotate the hub 18 within which the blades 14 arerigidly mounted. The two-part hub 18 is clamped together by bolts, notshown, and is connected to a drive spindle 22.

The drive spindle 22 is formed with a shoulder 24, the shoulder 24 beingconnected with a shoulder 26 integral with a hub shaft 28 by means of apair of nut and bolt assemblies, one of which is indicated by numeral30. The shoulder 24 on the drive spindle, or power shaft, 22 is alsoconnected with the two-part hub 18 by the aforementioned bolts, notshown. The hub shaft 28 has a cross bore, not shown, surrounded by aboss 68 within which the stub shaft ends of the roots 32 of theadjustable pitch blades 12 are supported by suitable bearing means, notshown. The roots 32 of the adjustable pitch blades are diametricallyopposed and extend radially outward as seen in FIGURE 1. Each blade root32 has a governor counterweight 34 drivingly connected thereto by intermeshing spline teeth indicated by numeral 36 and held in assembledrelation by a nut 38. The root portions 32 of the adjustable pitchblades 12 are journalled in the twopart hub 18 by ball bearing means '40for rotation about their longitudinal axes to different pitch positions.

The hub shaft 28 extends forwardly of the hub 18, and the spinner 10 isattached to the end thereof by means of a cap screw 42. Accordingly, thespinner shell 10 is connected to rotate with the hub 18. A sliderasembly 44 is supported for reciprocable movement on the hub shaft 28 bymeans of a pair of spaced bushings, not shown, carried by the sliderassembly 44. The slider assembly 44 is formed with a pair of radiallyextending arms 46, the purpose of which will be described hereinafter.

A guide assembly 48 is supported for reciprocable movement on the outerperiphery of the slider assembly 46, by suitable bushings, one of whichis depicted by the numeral 59. The guide assembly 48 is coaxial with theslider assembly 44, and the slider assembly is coaxial with the hubshaft 28. The guide assembly 48 is formed with a flange 52 constitutinga retainer for one end of a helical compression spring 54. The other endof the compression spring 54 engages a retainer 56 clamped between thespinner shell 10 and the hub shaft 23 by the screw 42. In order toadjust the preload of the governor spring 54, one or more shims 58 maybe inserted between the retainer 56 and the outer end of the governorspring 54.

Each counterweight 34 is connected to one of the arms 46 of the sliderassembly 44 by a connecting link 60. The

inner ends of the connecting link 60 are connected by crank pins 62 totheir respective counterweights 34 and the outer ends of the connectinglinks 60 are connected by pins 64 to one of the arms 46 on the sliderassembly 44. The outer ends of the connecting links 6% are formed withcam surfaces 66, the purpose of which will be described in particularhereinafter.

The adjustable pitch blades 12 are shown in the minimum positive pitchposition in FIGURES l and 2. This position is determined by physicalengagement of the slider assembly 44 with a boss 68 within which theinner ends of the roots of the adjustable pitch blades are journalled.The end of the slider assembly 44 is depicted by numeral 44a.

The high pitch position of the blades 12 is determined by engagementbetween portions 35 of the governor fly- Weights' 34 and the hub shaft28, as depicted in FIGURE 3. The slider assembly 44 and the links 60constitute coordinating means for maintaining the pitch position of theadjustable pitch blades 12 at right angles.

The governor assembly disclosed is of the droop type, that is thegovernor mechanism will maintain the speed of turbine rotation within apredetermined range, for instance 190 r.p.s. to 215 r.p.s., with anominal speed setting of 202 r.p.s. When the turbine is withdrawn fromthe air stream, the spring 54 will move the guide assembly 48 and theslider assembly 44 to the position shown in FIGURE 2 so that theadjustable blades 12 will be at the mechanical low pitch stop position.

When the turbine is positioned in a moving air stream the air impingingon the fixed pitch blades 14 and the adjustable pitch blades 12 willimpart rotation to the hub 18 and the power output shaft 22. Theadjustable pitch blades 12 are controlled by the spring-fiyweightgovernor so as to maintain the speed of turbine rotation within apreselected range. As the wind velocity increases, the turbine speedwill increase thereby causing the governor fiyweight 34 to rotate in thecounter-clockwise direction as viewed in FIGURE 2 so as to furthercompress the spring 34 and increase the angle of the blades 12. As theangle of the blades 12 is increased, the slider assembly 44 moves to theleft as viewed in FIGURE 2, compressing the spring 54. When apredetermined high angle of the blades is obtained, the cam surfaces 66On the connecting links 60 will engage the flange 52 on the guideassembly 48 as shown in FIGURE 3 so as to further compress the governorspring 54 and separate the flange 52 of the guide assembly from the arms46 of the slider assembly 44. The coaction of the cams 66 with the guideassembly 46 permits a larger blade angle excursion while maintaining asubstantial linear relationship between blade angle and turbine speed.

As seen in the graph of FIGURE 4, turbine speed varies substantiallylinearly with the angle of the adjustable pitch blades 12 betweenapproximately a positive 20 and a positive 85.

While the embodiment of the invention as herein disclosed constitutes apreferred form, it is to be understood that other forms might beadopted.

What is claimed is as follows:

1. An air driven turbine including, a hub, a blade journalled in saidhub for pitch adjustment between predetermined low and high bladeangles, a rotatable shaft connected with said hub so as to be driventhereby, a governor counterweight supported for rotation about the axisof said blade, means connecting said counterweight and said blade foradjusting the pitch position thereof, resilient means for opposingmovement of said counterweight, and a link operatively interconnectingsaid counterweight and said resilient means and having cam means thereoncoacting with said resilient means to increase the range of pitchadjustment of said blade within the governing regime.

2. An air driven turbine including, a hub, a blade journalled in saidhub for pitch adjustment, a rotatable shaft connected with said hub soas to be driven thereby,

governor flyweight means operatively connected with said blade foradjusting the pitch position thereof, resilient means for opposingmovement of said governor flyweight means, and a link operativelyinterconnecting said governor flyweight means and said resilient meansand having cam means thereon for increasing the range of pitchadjustrnent of said blade within the governing regime.

3. An air driven turbine including, a hub, a blade journalled in saidhub for pitch adjustment, a rotatable shaft connected with said hub soas to be driven thereby, centrifugally responsive fiyweight meansoperatively connected with said blade for adjusting the pitch positionthereof, resilient means for opposing movement of said flyweight meanscomprising a spring, a slider assembly operatively engaging one end ofsaid spring and mounted for reciprocable movement for compressing saidspring, a guide assembly coaxial with said slider assembly and mountedfor reciprocation relative thereto, said guide assembly operativelyengaging said spring for compressing the same, and a link operativelyinterconnecting said flyweight means and said slider assembly and havingcam means thereon engageable with said guide assembly for increasing therange of pitch adjustment of said lade within the governing regime.

4. An air driven turbine including, a hub, a blade journalled in saidhub for pitch adjustment, a rotatable shaft connected with said hub soas to be driven thereby, centrifugally responsive flyweight meansoperatively connected with said blade for adjusting the pitch positionthereof, resilient means for opposing movement of said fiyweight meanscomprising a spring mounted coaxially of said shaft, a slider assemblycoaxial with said shaft and operatively engageable with one end of saidspring for compressing the same, a guide assembly coaxial with saidshaft and supported for reciprocable movement on said slider assembly,said guide assembly operatively engaging said spring for compressing thesame, and a link operatively interconnecting said fiyweight means andsaid slider assembly and having cam means thereon engageable with saidguide assembly for increasing the range of pitch adjustment of saidblade within the governing regime.

5. An air driven turbine including, a hub, a blade journalled in saidhub for pitch adjustment, a rotatable shaft connected with said hub soas to be driven thereby, a governor counterweight operatively connectedwith said blade for imparting pitch adjusting movement thereto andsupported for rotation in said hub about the axis of said blade, agovernor spring coaxial with said shaft for opposing movement of saidcounterweight, and a link operatively interconnecting said counterweightand said spring and having cam means thereon for increasing the range ofpitch adjustment of said blade within the governing regime.

6. An air driven turbine including, a hub, having a centrally disposedshaft, 21 blade rotatably journalled in said hub for pitch adjustment, agovernor counterweight operatively connected to said blade for adjustingthe pitch position thereof and supported for rotation in said hub aboutthe axis of said blade, a governor spring supported coaxially of saidhub shaft for opposing movement of said counterweight, and a linkoperatively interconnecting said counterweight and said spring andhaving cam means thereon for increasing the range of pitch adjustment ofsaid blade within the governing regime.

7. The air driven turbine set forth in claim 6 including a sliderassembly reciprocably mounted on said hub shaft and operatively engagingone end of said governor spring, a guide asembly reciprocably supportedon said slider assembly and engaging one end of said governor spring,and wherein said link is pivotally connected to said slider assembly andsaid cam means are engageable with said guide assembly.

8. An air driven turbine including, a hub, a plurality of bladesjournalled in said hub for pitch adjustment and said spring and havingcam means thereof for increasing the range of pitch adjustment of saidblades within the governing regime.

References Cited in the file of this patent UNITED STATES PATENTSSquires May 24, 1938 Hook et al. v Oct. 21, 1958

